The increased congestion of highways combined with high driving speeds, creates a situation which requires a driver to judge the separation of his vehicle and the vehicle he is following, and to correlate this distance with a speed which is safe enough to bring his vehicle to a stop if need arises. Correlating the distance to a safe speed may not be straightforward, especially at relatively higher speeds where the separation between vehicles should be more than one car's length per each 10 miles an hour of speed generally recommended at lower speeds.
The present invention includes a projector device, the observable color (or colors) of which varies at different distances of the observer and represents his distance from it, and a memory aid pattern means to correlate these distances with the required safe speeds.
Beside keeping a safe distance from the preceeding vehicle, a driver on a high-speed highway deals with the problem of judging how fast his front vehicle is stopping when it does so. More technically, what the deceleration, i.e., negative acceleration, of his front vehicle is. Unfortunately, the brakelights, although indicating the application of brakes, do not show the amount of deceleration produced. Consequently, the judgement of the amount of deceleration of the front vehicle by a driver following it is based upon observation of how fast he approaches his front vehicle. This kind of judgement requires some time, causing delay in deciding what amount of braking is needed to avoid collision with the front decelerating vehicle. The delay time such introduced may be longer for a driver following a vehicle whose driver uses his brakes more often and for minor speed adjustments, since naturally, one would be inclined to ignore the brakelights. In sudden stops, the delay in determining that heavy braking is needed to avoid collision, may necessitate even heavier braking, increasing the chance of being bumped into by a vehicle which may be following closely from behind. Furthermore, a vehicle may be decelerated to some extent even without use of brakes and by merely reducing the amount of accelerator used and with no warning to the following driver.
The presently disclosed system helps the driver to determine his safe speed, and to make safer speed adjustment in accordance with the amount of deceleration of his front vehicle.